An audio signal (e.g., music or speech) usually includes many components, such as pitch, volume, timbre and time. The modification of the time aspect of an audio signal, which is generally referred to as time-scale modification of the audio signal, is very useful for certain applications, such as voice-mail, dictation-tape playback or post synchronization of film and video. FIG. 1(A)-FIG. 1(C) depict example diagrams showing a basic principle of time-scale modifications of an audio signal. As shown in FIG. 1(A), an original audio recording 100 includes segments 102, 104 and 106 of a same time length L0. Time-scale modifications can be performed on the original audio recording 100 to expand or compress the segments. As shown in FIG. 1(B), the segments 102, 104 and 106 are expanded to different extents to have time lengths longer than the original time length L0. On the other hand, as shown in FIG. 1(C), the segments 102, 104 and 106 are compressed to different extents to have time lengths shorter than the original time length L0. Usually, time-scale modifications of an audio signal speed up or slow down the audio signal without changing the pitch of the audio signal which corresponds to a fundamental period of the audio signal.